Air mass flow sensor of silicone base thin-film structure

Abstract

The invention relates to a mass air flow sensor with silica-based thin-film structure on the basis of the MEMS technique. The silica-based material 1 is covered with a layer of insulation film 2, the middle part of the whole structure is etched with a heat insulation cavity 5, and a heating resistance 3 and a resistance temperature detector 4 are arranged on the base material by one time by adopting the MEMS technique. For the arrangement, the heating resistance 3 is arranged on the insulation film 2 of the heat insulation cavity 5, and the resistance temperature detector is arranged on the insulation film on the silica-based material. By adopting the mass air flow sensor of the invention, a hot type mass air flow sensor which has high measuring precision, low power consumption, large measuring range, good consistency of measurement, low cost and constant temperature difference.

Description

technical field [0001] The invention relates to an air mass flow sensor suitable for measuring the intake air volume of an automobile engine, in particular to an air mass flow sensor composed of a silicon-based film structure sensitive element. Background technique [0002] Generally, as an air mass flow sensor for measuring the intake air volume of an engine of a car, etc., the air flow rate is measured by measuring the temperature difference between the upstream resistor and the downstream resistor of the heating resistor, or the heating current is measured by controlling the temperature difference between the heating resistor and the fluid to be constant. to measure air flow. The method of controlling the temperature difference between the heating resistor and the fluid to be constant is called the constant temperature difference method. [0003] The constant temperature differential thermal air mass flow sensor consists of a heating resistor and a temperature measuring ...

AI Technical Summary

Problems solved by technology

The existing technology usually uses two independent thermistors as the heating resistor and the temperature measuring resistor respectively. Due to the problem of process batching, it is difficult to ensure that the two have exactly the same temperature sensitivity coefficient.

Moreover, the requirements for the thermal dissipation coefficients of the two resistors are also a contradiction

In addition, the use of two independent thermistors also makes the cost considerable, and the consistency is difficult to guarantee

Due to the influence of the thermistor packaging form, the air mass flow sensor using two independent thermistors still has defects such as the inability to improve the measurement accuracy, the inability to reduce power loss, and the limited measurement range.

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